Term | Definition |
mass number | the sum of the number of neutrons and protons in an atomic nucleus |
Avogadro's number | the number of atoms in a mole
6.02×1023 mol−1 |
law of conservation of mass | states that matter can be changed from one form into another, mixtures can be separated or made, and pure substances can be decomposed, but the total amount of mass remains constant |
mole | unit of measurement that expresses amounts of a chemical substance |
atom | the smallest unit that defines the chemical elements and their isotopes |
deuterium | one of two stable isotopes of hydrogen |
law of definite proportions | a.k.a. Proust's Law, states that a chemical compound always contains exactly the same proportion of elements by mass |
proton | a subatomic particle with a positive electric charge of 1 elementary charge and mass slightly less than that of a neutron |
tritium | a radioactive isotope of hydrogen |
molar mass | the mass of a given substance |
protium | the most common isotope of the element hydrogen, with one proton and no neutrons |
neutron | subatomic particle with no net electric charge and a mass slightly larger than that of a proton |
isotope | variants of a particular chemical element such that while all isotopes of a given element have the same number of protons in each atom, they differ in neutron number |
average atomic mass | the mass of an isotope of an element in atomic mass units |
law of multiple proportions | Dalton's law, if two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers |
atomic number | the number of protons found in the nucleus of an atom of that element |
atomic mass unit | the standard unit that is used for indicating mass on an atomic or molecular scale
1.66053892 × 10-27 kilograms |
electrons | subatomic particle with a negative elementary electric charge |